Synergetic noise absorption and anti-icing for aircrafts

ABSTRACT

Systems and methods are provided for an inductive coil anti-icing and noise absorption system. In certain versions, the inductive coil anti-icing and noise absorption system may include an inductive coil and a skin. The inductive coil may generate electromagnetic fields and may electromagnetically couple with the skin. The skin, upon electromagnetically coupling with the inductive coil, may increase in temperature and the increase in temperature may melt or prevent the formation of ice on the skin. The skin or a portion of the skin may be porous and may allow incorporation of a sound absorbing liner. The sound absorbing liner may attenuate noise generated by the aircraft (e.g., noise generated by the aircraft engine). Certain versions may include a plurality of inductive coils and a plurality of skins.

TECHNICAL FIELD

The disclosure relates generally to aircrafts and, more particularly, toaircraft anti-icing, de-icing, or both, and noise absorption.

BACKGROUND

Ice may form on surfaces of an aircraft. Currently, aircraft engines mayinclude anti-icing or de-icing systems that feature a swirl system thatuses hot gases to transfer heat to a leading edge of an engine nacelleto anti-ice and/or de-ice the engine nacelle. Such a swirl system may bepressurized and thus, to maintain the needed pressure, may need to belocated within a pressurized chamber separate from other aircraftcomponents. The pressurized system may be incompatible with otheraircraft components, such as aircraft acoustic treatment, and thus anyspace used for the swirl system may be space that is not used for theother components. Such a system may also need to be placed in the engineinlet of an aircraft engine (i.e., the portion of the nacelle forward ofthe engine fans) as ice build-up tends to occur most on a leading edge.

SUMMARY

Systems and methods are disclosed herein providing a noise absorptionand an anti-icing, de-icing, or both anti-icing, de-icing system. Theapparatus may include a nacelle comprising a skin. The skin may be madefrom at least a ferromagnetic metal and/or alloy, at least a portion ofthe skin may be porous, at least a portion of the skin may form a flowsurface of the nacelle, and the skin may at least partly define acavity.

In certain such implementations of the apparatus, the portion of theskin that is porous may include a porous facesheet and the skin mayfurther include a backsheet coupled to the porous facesheet. Thebacksheet may allow air to flow through the porous facesheet to reducenoise without the air flowing into other regions of the engine nacelle.In some such implementations of the apparatus, the skin may furtherinclude a ferromagnetic metal and/or alloy component, at least partlymade of the ferromagnetic metal and/or alloy, disposed between thefacesheet and the backsheet. The ferromagnetic metal and/or alloycomponent may allow the space between the facesheet and the backsheet tobe heated. In some such implementations, the ferromagnetic metal and/oralloy component may be a septum. Air may flow from one side of theseptum to the other to reduce noise. The septum or a portion of theseptum may be heated and heating the septum or a portion of the septummay vary air pressure on one or the other side of the septum. Thedifference in pressure may aid in the flowing of air through the septum.In certain additional such implementations of the apparatus, the porousfacesheet may include or be coated with the ferromagnetic metal and/oralloy and at least a portion of the skin may be located on a leadingedge of the nacelle. In certain additional such implementations of theapparatus, the skin may further include a support component between theporous facesheet and the backsheet. The support sections may strengthenthe skin. In certain such implementations, the support component may bea honeycomb. Honeycomb may allow weight efficient strengthening of theskin, allowing strength to be added with little increase in weight.

In certain additional such implementations of the apparatus, the portionof the skin that is porous may include at least one of a plurality ofperforations, a plurality of perforations, a mesh, a porous mat, or afeltmetal-like regular or irregular cross-linked structure made of aferromagnetic metal and/or alloy wire, sponge, or other porous media.

In certain additional such implementations of the apparatus, the portionof the skin that is porous may be configured to attenuate noise.

In certain additional such implementations of the apparatus, theapparatus may further include an inductive coil located at least partlywithin the cavity and configured to be electromagnetically coupled tothe skin. The inductive coils may be a sandwich configuration inductivecoil, a pancake configuration inductive coil, a solenoid configurationinductive coil, or another configuration of inductive coil. The skin maybe configured to increase in temperature when electromagneticallycoupled to the inductive coil. In certain such implementations of theapparatus, the inductive coil may be a first inductive coil and theapparatus may further include a second inductive coil located at leastpartly within the cavity. The two (or more) inductive coils may beconfigured to electromagnetically couple with two (or more) portions ofthe skin. The different sections of the skin may be optimallyelectromagnetically coupled to inductive coils of different inductances.Having two (or more) inductive coils may allow portion of the skin to beoptimally electromagnetically coupled. In certain such implementations,the skin may be a first skin, the ferromagnetic metal and/or alloy maybe a first ferromagnetic metal and/or alloy, and the apparatus mayfurther include a second skin such that the second skin at least partlydefines the cavity, the second skin may be made of the firstferromagnetic metal and/or alloy and/or a second ferromagnetic metaland/or alloy, the first inductive coil may be configured to beelectromagnetically coupled to the first skin, and the second inductivecoil may be configured to be electromagnetically coupled to the secondskin. In certain such implementations, the second skin may benon-porous. The second skin may be non-porous to reduce aerodynamic dragof the engine nacelle.

In certain additional such implementations of the apparatus, theapparatus may further include a support structure within the nacellesuch that the support structure may partly define the cavity and theskin may be located forward of the support structure. In such examples,the cavity, formed by at least the support structure and the skin, maybe pressurized.

In some implementations, an aircraft including the apparatus may beprovided. The aircraft may include a fuselage, a wing coupled to thefuselage, an engine coupled to the wing and/or the fuselage, such thatat least one of the fuselage, the wing, and/or the engine may includethe apparatus.

In another example, a method may be provided. The method may includereceiving a skin including at least a porous facesheet and a backsheetsuch that at least a portion of the skin includes a ferromagnetic metaland/or alloy and coupling the skin to an engine to form at least aportion of an engine nacelle such that at least a portion of the skinforms a flow surface of the engine nacelle.

In certain such implementations of the method, the method may furtherinclude installing an inductive coil within a cavity of the enginenacelle and electrically connecting the inductive coil to a powersupply. In certain such implementations, the method may further includepositioning at least a portion of the skin within 1-2 inches of at leasta portion of the inductive coil. In certain additional suchimplementations, the skin may be a first skin, the inductive coil may bea first inductive coil, the ferromagnetic metal and/or alloy may be afirst ferromagnetic metal and/or alloy, and the method further includecoupling a second skin to the engine such that a portion of the secondskin may include the first ferromagnetic metal and/or alloy and/or asecond ferromagnetic metal and/or alloy, installing a second inductivecoil within the cavity of the engine nacelle such that at least aportion of the second skin is within 1 foot of at least a portion of thesecond inductive coil, and electrically connecting the second inductivecoil to the power supply or a second power supply. In certain otheradditional such implementations, the power supply may be a first powersupply and the method may further include connecting the secondinductive coil to the second power supply.

The scope of the invention is defined by the claims, which areincorporated into this section by reference. A more completeunderstanding of embodiments of the invention will be afforded to thoseskilled in the art, as well as a realization of additional advantagesthereof, by a consideration of the following detailed description of oneor more embodiments. Reference will be made to the appended sheets ofdrawings that will first be described briefly.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example aircraft in accordance with thedisclosure.

FIG. 2 illustrates an example aircraft engine in accordance with thedisclosure.

FIGS. 3A-C illustrate a portion of an example aircraft engine withvarious inductive coil anti-icing and noise absorption systems inaccordance with the disclosure.

FIGS. 4A-C illustrate various example skin configurations in accordancewith the disclosure.

FIG. 5 illustrates a flowchart detailing an example operation of aninductive coil anti-icing and noise absorption system in accordance withthe disclosure.

FIG. 6 illustrates a flowchart detailing an assembly process of anaircraft component containing an inductive coil anti-icing and noiseabsorption system in accordance with the disclosure.

Examples of the disclosure and their advantages are best understood byreferring to the detailed description that follows. It should beappreciated that like reference numerals are used to identify likeelements illustrated in one or more of the figures.

DETAILED DESCRIPTION

Aircrafts may include anti-icing and/or de-icing systems. Currently,aircrafts may include an anti-icing system that contains a swirl systemthat uses hot gases to transfer heat to an engine nacelle to anti-icethe engine nacelle. Such a swirl system may be pressurized and thus, tomaintain the needed pressure, the swirl system may need to be containedwithin the engine nacelle in a pressurized portion of the enginenacelle.

Aircraft engine nacelles may also include acoustic treatment to lowersound levels within and outside of the aircraft. The acoustic treatmentmay be incompatible with the swirl system and thus may only bepositioned in areas of the aircraft not occupied by the swirl system.However, to maximize noise reduction, it may be desirable to includeacoustic treatment in areas of the aircraft that may also requireanti-icing. A certain such area is the engine inlet of an aircraftengine, where both anti-icing and noise reduction treatment would bebeneficial. Current systems lead to an either or situation wheredevoting greater space to anti-icing systems leads to having less ofsuch space available for noise reduction systems.

FIG. 1 illustrates an aircraft in accordance with the disclosure. InFIG. 1, aircraft 100 includes an engine 102, a fuselage 104, an engine106, and a tail 108. The aircraft 100 may be any type of aircraft.

The engine 102 may be any type of aircraft engine that may benefit fromanti-icing and noise reduction features. Non-limiting examples of suchengines include turbofans, turboprops, and turbojets. For the purposesof this disclosure, “anti-ice” or “anti-icing” may refer to either orboth of the prevention of ice formation on as well as the melting of anyice that has built up on any surface of the aircraft. The fuselage 104may be any type of aircraft fuselage. The wing 106 and the tail 108 maybe control surfaces of the aircraft 100. The wing 106 and the tail 108may include flaps. One, some, or all of the engine 102, the fuselage104, the wing 106, and the tail 108 of the aircraft 100 may includeversions of the inductive coil anti-icing system as described herein.Additionally, noise absorption features integrated within the inductivecoil anti-icing system may also be present.

In certain examples, the inductive coil anti-icing system, with orwithout integrated noise absorption features, may be located on anengine nacelle. FIG. 2 illustrates an aircraft engine in accordance withthe disclosure. The aircraft engine 102 may include a nacelle 210 and anengine fan 246. The aircraft engine 102 in FIG. 2 may be, for example, aturbofan engine.

FIG. 2 also includes a leading edge region 212. The leading edge region212 may be at least part of the portion of the nacelle 210 before theengine fan 246. In certain examples, perforation based noise treatmentsapplied to engines may be located within the leading edge region 212.That is, the noise treatment may be located upstream, as defined by theairflow, of the engine fan 246. In certain examples, perforation basednoise treatments may be effective upstream of the engine fan 246.

The features of the engine nacelle within the leading edge region may befurther illustrated in FIGS. 3A-C. FIGS. 3A-C illustrate the leadingedge region 212 of FIG. 2 in further detail. FIGS. 3A-C illustrate aportion of an aircraft engine with various inductive coil anti-icing andnoise absorption systems in accordance with the disclosure.

The examples of the inductive coil anti-icing systems described in FIGS.3A-C may all be compatible with aircraft noise treatments, such asperforation based noise treatments. Accordingly, such systems may moreefficiently use the space available on an aircraft, such as spaceavailable on an aircraft engine, by having the same space be occupied bya system that performs the dual role of anti-icing and noise abatement.

Note that while FIGS. 3A-C illustrate a cutaway of a portion of anengine nacelle, the various components illustrated in FIGS. 3A-C mayextend across the entire engine nacelle (e.g., may extend across theentire circumference or a portion of the circumference of an enginenacelle) or may be applied to other areas of the aircraft such as thecontrol surfaces or the fuselage.

FIG. 3A highlights an example of an inductive coil anti-icing and noiseabsorption system located within a leading edge of an engine nacelle.Engine nacelle leading edge 212A of FIG. 3A includes a first skin 316, asecond skin 314, a first inductive coil 320, a second inductive coil318, a power source 322, electrical connections 324 and 326, a capacitor328 (as well as additional capacitors where certain such additionalcapacitors may be configured to decouple), a non-ferromagnetic nacelleskin 330, bulkhead 332, and a controller 350. The first skin 316 and thesecond skin 314 may partly define a cavity that may contain the firstinductive coil 320 and the second inductive coil 318. Certain examplesmay also include the bulkhead 332 and the bulkhead 332 may also partlydefine the cavity. In certain examples, the first skin and/or the secondskin may form a portion of the engine nacelle. In certain such examples,the first skin and/or the second skin may not form the entirety of theengine nacelle. Such examples may locate elements of the systemdescribed herein within the portion of the engine nacelle formed by thefirst skin and/or the second skin.

The first skin 316 may be a single component (e.g., one sheet of metal)or may be multiple components (e.g., multiple sheets of metal coupledtogether). At least a portion of the first skin 316 may be ferromagneticmetal. For the purposes of this disclosure, “ferromagnetic metal” mayrefer to ferromagnetic materials made from one type of metal or toferromagnetic materials made an alloy (in other words, a ferromagneticalloy). Certain examples may include components made from bothferromagnetic metals and ferromagnetic alloys. Such examples may includesystems with multiple skins or panels. The multiple panels in suchexamples may include at least one ferromagnetic metal panel and at leastone ferromagnetic alloy panel. For examples of the first skin 316assembled from multiple components, at least a portion of one of thecomponents may be ferromagnetic metal. In certain such examples, theferromagnetic metal may contain ferromagnetic metals such as INCONEL,nichrome, graphite based materials, or other types of material. Suchmaterials may be available from a variety of vendors. Non-limitingexamples of appropriate ferromagnetic metals include alloys containingchrome, steel, iron, aluminum, nickel, cobalt, and titanium, but otherexamples may use other ferromagnetic metals. Certain examples mayinclude one ferromagnetic metal, or multiple different ferromagneticmetals. Any ferromagnetic metal may be used with the systems andapparatus of this disclosure, including ferromagnetic metals withmagnetic susceptibilities leading to certain current densities atcertain frequencies as appropriate, as to be understood by one skilledin the art. In certain examples, current densities of the ferromagneticmetal may be proportional to frequency. Appropriate magneticsusceptibility may include magnetic susceptibilities of less than 2,less than 5, less than 10, less than 20, and up to 10,000, or above10,000. In certain such examples, a higher magnetic susceptibility mayallow for a lower frequency. Lower frequencies may be used, if desired,due to, for example, electromagnetic interference considerations.Certain examples may select the ferromagnetic metal based on acombination of the magnetic susceptibility, the frequency, the availablematerials, and other considerations (such as environmental, packaging,reliability, etc.). The ferromagnetic metal may be a smart susceptorthat may be tuned to be heated to specific temperatures whenelectromagnetically coupled. A smart susceptor may be a ferromagneticmetal with a known Curie temperature at which susceptibility of themetal and/or alloy to a magnetic field may start to decrease.

The first skin 316 may at least partially define a cavity. The cavitymay be an interior form of, for example, the engine nacelle and may atleast partially contain a first inductive coil. Inductive coilsdescribed within this disclosure may be pancake, sandwich, solenoid,etc. configurations of inductive coils. The first inductive coil 320may, when powered, produce a first electromagnetic field. Theferromagnetic metal within the first skin 316 may couple with and/orcapture the first electromagnetic field produced by the first inductivecoil 320. When the metal within the skin 316 captures the firstelectromagnetic field, heat may be generated. The heat may prevent theformation of ice or melt any ice on the outside surface of the firstskin 316 (e.g., the surface of the skin exposed to airflow).

In certain examples, the first skin 316 may be porous. That is, at leasta portion of the first skin 316 may include perforations. In certainexamples, the perforations may be formed by, for example, holes withinthe first skin 316 or by having at least a portion of the first skin 316be produced from a mesh material. In certain such examples, the firstskin 316 may include at least a porous facesheet and a backsheet. Thefacesheet and the backshseet of the first skin 316 may be elements of anacoustic liner. In certain examples, the porous facesheet may work inconjunction with a back cavity and a non-porous backsheet or backsurface to set up a Helmholtz resonator type acoustic liner. Possibleconfigurations of the first skin 316 may be further illustrated in FIGS.4A-C.

The second skin 314 may be similar to the first skin 316. The secondskin 314 may also be constructed from a single component (e.g., onesheet of metal) or may be multiple components (e.g., multiple sheets ofmetal coupled together) and at least a portion of the second skin 314may be ferromagnetic metal. The ferromagnetic metal of the second skin314 may be the same ferromagnetic metal of the first skin 316 or may bea different ferromagnetic metal.

The second inductive coil 318 may also be similar to the first inductivecoil 320. However, in certain examples, the positioning, length, andcoil configuration of the second inductive coil 318 may differ from thefirst inductive coil 320.

The second inductive coil 318 may, when powered, produce a secondelectromagnetic field. The ferromagnetic metal within the second skin314 may couple with and/or capture the second electromagnetic field andgenerate heat. The heat generated by the second skin 314 may alsoprevent the formation of ice or melt any ice on the outside surface ofthe second skin 314.

In certain examples, the second skin 314 may also be porous, howeverother examples may have a non-porous second skin 314. A non-poroussecond skin may allow for noise decreasing perforations to beconcentrated in areas where they reduce noise the most (e.g., on theinside of the engine nacelle) and may, for example, decrease cost and/oraerodynamic drag resulting from locating porous skins in areas wherethey are less useful. In certain examples, a porous first skin 316 maybe located on an inside of the engine nacelle (e.g., the portion of theengine nacelle that intakes air) while a non-porous second skin 314 maybe located on an outside of the engine nacelle. In such a configuration,the porous first skin 316 may be most effective at attenuating noise onthe inside of the engine nacelle. On the outside of the engine nacelle,where noise attenuation through the use of a porous skin is lesseffective, the second skin 314 may be non-porous to decrease aerodynamicdrag.

In certain examples, the second skin 314 may be constructed from asingle component (e.g., one sheet of metal) or multiple components(e.g., multiple sheets of metal coupled together). In examples whereeither the first skin 316 and/or the second skin 314 are made ofmultiple components, one, some, or all of the components may include theferromagnetic metal. When less than all of the components include theferromagnetic metal, the ferromagnetic metal may be in thermallyconductive contact with other components, such as the outer skin (e.g.,the layer of the skin exposed to airflow), so as to heat the othercomponents. As such, these other components may also be heated toprevent the formation of ice or melt any ice on the components.

The inductive coils 318 and 320, which produce the electromagneticfields to heat the first skin 316 and the second skin 314, may becoupled to the power source 322 (e.g., be able to receive currentflowing from the power source 322). The power source 322 may be an ACpower source, though other examples may use a DC power source. The powersource 322 may be coupled to the first inductive coil 320 and/or thesecond inductive coil 318 through electrical connections. In FIG. 3A,the power source 322 may be coupled to the first inductive coil 320 viathe electrical connection 326 and may be coupled to the second inductivecoil 318 via the electrical connection 324. Additionally, the firstinductive coil 320 may be electrically coupled to the second inductivecoil 318 through an electrical connection. In FIG. 3A, a capacitor 328may be installed within the electrical connection connecting the firstinductive coil 320 and the second inductive coil 318.

The example shown in FIG. 3A may have the first inductive coil 320 andthe second inductive coil 318 may be coupled in series. In such anexample, the capacitor 328 may be a compensating capacitor. In certainconfigurations, having two inductive coils connected in series may shiftthe resonant frequency of at least one inductive coil away from theoptimal frequency. Such a situation may be compensated for by theinstallation of the compensating. The value of the compensatingconnector may be selected to affect the amount of current flowing withinthe coils.

The first inductive coil 320 and the first skin 316 may form a firstsystem. The second inductive coil 318 and the second skin 314 may form asecond system. The compensating capacitor may affect an amount ofcurrent flowing through the first inductive coil 320 and/or the secondinductive coil 318 such that the first system and/or the second systemmay be operating substantially within the resonant frequency of thefirst system and/or the second system.

In a certain example, the resonant frequency of the first system and/orthe second system may be determined through the thickness of the firstskin 316 and/or the second skin 314, respectively. The characteristicsof the first system and/or the second system, such as the resistance andthe inductance of the first system and/or the second system, may beevaluated and the capacitance of the capacitor 328 may then bedetermined responsive to the other characteristics of the first systemand/or the second system. The capacitor 328 may be an off-the-shelfcapacitor or may have a custom capacitance. The capacitor 328 may beselected to have a capacitance to influence the first system and/or thesecond system such that the first system and/or the second system may beoperating substantially within the resonant frequency of the firstsystem and/or the second system.

The controller 350 may regulate the power source 322. The controller 350may, in certain examples where the power source 322 is an AC powersource, determine an optimal switching frequency of the power source322. The controller 350 may regulate the switching frequency of thepower source 322 automatically so as to “tune” the output frequency ofthe power source 322 to the resonant frequency of the first systemand/or the second system. In other words, the controller 350 may “scan”the frequency range of the power source 322 until the controller 350finds a spot within the frequency range where the impedance is minimalor current reaches its maximum value.

In addition, the controller 350 may also determine when to provide powerto the first inductive coil 320 and the second inductive coil 318. Incertain examples, the controller 350 may provide power to the inductivecoils based on a schedule such as a timetable or power providingschedule, may provide power when commanded to by an operator, or mayprovide power to the inductive coils when an environmental factor, suchas the presence of ice on a surface of the aircraft, is detected.

Certain examples may include the nacelle skin 330 and/or the bulkhead332. The nacelle skin 330 may be a portion of the nacelle that does notinclude inductive coils positioned behind the nacelle skin 330 to heatthe skin. In certain examples, the nacelle skin 330 may not includeferromagnetic metal within its composition. The bulkhead 332 may supportpart of the nacelle. Though certain examples may use the bulkhead 332 tofully seal, and thus pressurize, the cavity, the inductive coilanti-icing system does not require the cavity to be pressurized.Accordingly, certain examples may not include the bulkhead 332.

FIG. 3B highlights another example of an inductive coil anti-icing andnoise absorption system located within a leading edge of an enginenacelle. Similar to FIG. 3A to the engine nacelle leading edge 212A,engine nacelle leading edge 212B of FIG. 3B may include the firstinductive coil 320, the second inductive coil 318, the first skin 316,the second skin 314, the power source 322, and the controller 350.

However, unlike in FIG. 3A, the first inductive coil 320 and the secondinductive 318 may be coupled in parallel to the power source 322.Electrical connector 334A may be coupled to the power source 322 and thesecond inductive coil 318. Electrical connector 334B may be coupled tothe power source 322 and the first inductive coil 320. The electricalconnector 334A may include a capacitor 336A and an electrical connector334B may include the capacitor 336B. The first inductive coil 320 andthe capacitor 336B may form a first system. The second inductive coil318 and the capacitor 336A may form a second system. The capacitors 336Aand 336B may be capacitors with capacitances chosen to equalize theimpedance of the first system and the second system. Such aconfiguration may allow for substantially equal flow of current betweenthe first and second system. In certain other examples, the power source322 and the controller 350 may represent a dual-frequency powersupplying system. In such examples, the controller 350 may controllerthe frequency of the power source 322.

FIG. 3C highlights a further example of an inductive coil anti-icing andnoise absorption system located within a leading edge of an enginenacelle. Engine nacelle leading edge 212C of FIG. 3C may also be similarto the engine nacelle leading edge 212A of FIG. 3A. However, where FIG.3A includes one power source, the example of the inductive coilanti-icing and noise absorption system in FIG. 3C includes two powersources; power sources 338A and 338B. The power source 338A may becoupled to the first inductive coil 320 via the electrical connector3343 while the power source 338B may be coupled to the second inductivecoil 318 via the electrical connector 334A.

The controller 350 may control the amount of power that each powersource supplies to the respective inductive coil. In certain examples,the controller 350 may include algorithms determining the amount ofcurrent and/or the duration of power supplied to each inductive coil.Additionally, certain other examples may, instead of including two powersources, include a single power source configured to provide power toeither of the first inductive coil 320 or the second inductive coil 318or to both coils 318 and 320 in a dual-frequency power supplying mode.In such a configuration, the controller 350 may control the switching ofthe power source between providing power to either the first inductivecoil, the second inductive coil, or both.

It is appreciated that the examples of the inductive coil anti-icing andnoise absorption system described in FIGS. 3A-C are non-limiting. Otherexamples of the inductive coil anti-icing and noise absorption systemsare possible. For example, other examples may include only one inductivecoil or more than two inductive coils. Additionally, the inductive coilsof such examples may be electromagnetically coupled to only one skin,but other examples may include inductive coils that areelectromagnetically coupled to more than one skin (i.e., using theexample shown in FIGS. 3A-C as an example, one inductive coil may beelectromagnetically coupled to both the first skin 316 and the secondskin 314).

Additionally, the skin used in inductive coil anti-icing and noiseabsorption systems may also have various configurations. FIGS. 4A-Cillustrate various skin configurations in accordance with thedisclosure.

Skin 400A in FIG. 4A is such a skin configuration. The skin 400Aincludes a backsheet 438, a facesheet 440, a septum 442, and supportcomponents 444A-E. Additionally, FIG. 4A also includes an inductive coil418 to illustrate a possible position of an inductive coil if the skin400A is used as part of an inductive coil anti-icing and noiseabsorption system.

The backsheet 438 may be a solid sheet, though other examples mayinclude a backsheet with a porous portion or with gaps within thebacksheet. The backsheet 438, with or without support components, maystructurally support the facesheet 440 and prevent at least a portion ofthe facesheet 440 from flexing. The support components 444A-E mayadditionally aid in supporting the facesheet 440. In various examples,the support components 444A-E may be structural materials such as wallsand/or honeycombs that may lend additional stiffness to the skin 400A.

Referring back to the backsheet 438, in various examples, the backsheet438 may be constructed of a material that does not include ferromagneticmetals, but other examples may construct the backsheet 438 at least witha material that includes ferromagnetic metal. In such examples, theferromagnetic metal may couple with and/or absorb an electromagneticfield generated by the inductive coil 418 and produce heat throughcoupling with and/or absorbing the electromagnetic field. The heatproduced may then be conducted to the facesheet 440.

The facesheet 440 may, in certain examples, be a porous facesheet. Inother words, the facesheet 440 may be perforated. The perforations mayallow air to flow through the facesheet 440. In certain examples, theflow of air through the facesheet 440 may attenuate noise (i.e.,attenuate noise generated by the engine) through techniques describedherein.

In another example, the facesheet 440 may be a mesh and the perforationsmay be the open area of mesh. In yet a further example, the facesheet440 may include circular or non-circular holes or other features drilled(including laser drilled), formed, or otherwise produced into thefacesheet 440.

In certain examples, the facesheet 440 may be at least partiallyconstructed of a ferromagnetic metal. The material of the facesheet 440may include the ferromagnetic metal or the facesheet 440 may have anon-ferromagnetic metal base material with a ferromagnetic metal layerdeposited onto the base material (i.e., through a coating such as aplasma spray or a metallic aerosol spray or through deposition of theferromagnetic metal onto the base material).

The ferromagnetic metal of the facesheet 440 may couple with and/orabsorb electromagnetic waves generated by the inductive coil 418. Theferromagnetic metal may then increase in temperature and thus increasethe temperature of the facesheet 440. The increase in temperature maymelt any ice present on the flow surface portion of the facesheet 440 orprevent the formation on ice on the facesheet 440. The facesheet 440 mayincrease in temperature to any temperature, including 0 degrees Celsiusor above, above 5 degrees Celsius, or 10 degrees Celsius or above. Theflow surface may be any surface, such as a surface of the enginenacelle, exposed to the flow of air resulting from movement of avehicle.

The example in FIG. 4A may additionally include the septum 442. Theseptum 442, in certain examples, may be at least partially constructedof a ferromagnetic metal. The ferromagnetic metal may be the same or maybe different from the ferromagnetic metal that the facesheet 440 isconstructed from and may generate heat from coupling with and/orreceiving electromagnetic waves generated by the inductive coil 418. Insuch examples, the inductive coil 418 may be configured to couple withboth the facesheet 440 and the septum 442. Accordingly, the inductivecoil 418 may form a first system with the facesheet 440 and a secondsystem with the septum 442. The first system and the second system mayinclude two different resonant frequencies and the inductive coil 418may be configured to operate at either of the resonant frequencies. Incertain such examples, a controller may allow for the inductive coil 418to operate at either of the two resonant frequencies and allow theinductive coil 418 to switch between operating from one resonantfrequency to the other resonant frequency.

The septum 442 may also be a porous material and may allow air to flowfrom one side to the other side of the septum 442. In certain examples,the septum 442 may be heated to vary the speed of sound of the air orthe pressure of the air by, for example, changing the temperature aroundthe vicinity of the septum 442. The change in the speed of sound maychange the volume of the flow of air through the perforations of theseptum 442 and thus may aid in the attenuation of sound.

In addition to skin 400A in FIG. 4A, skin 400B in FIG. 4B may be anotherskin configuration. Skin 400B may include the backsheet 438, thefacesheet 440, the inductive coil 418, and the support components444A-C, all of which may be similar to the backsheet, facesheet,inductive coil, and support components of the skin 400A in FIG. 4A.Additionally, the skin 400B may also include a sound absorber 446.

The sound absorber 446 may be, for example, a sound absorber thatincludes a fiber bulk absorber, a foam layer, or a porous mat that mayallow air to flow through the mat. The sound absorber 446 may be atleast partially made from a ferromagnetic metal and may be made from amaterial that may aid in absorbing sound (e.g., a material such as aNiCr fiber bulk absorber). In certain examples where the sound absorber446 is at least partially made from a ferromagnetic metal, the facesheet440 may not be made from a material that includes a ferromagnetic metal.In such an example, the inductive coil 418 may electromagneticallycouple with the sound absorber 446 and the sound absorber 446 may, thus,generate heat. The heat generated by the sound absorber 446 may then beconducted to the facesheet 440, raising the temperature of the facesheet440 and melting any ice on the facesheet 440 or preventing the formationof ice on the facesheet 440.

Skin 400C of FIG. 4C may be a further skin configuration. Skin 400C mayinclude the backsheet 438, the facesheet 440, the inductive coil 418,and the support components 444A-E, all of which may be similar to thecorresponding components of the skin 400A in FIG. 4A.

In addition, the skin 400C may include an inner sheet 448. The innersheet 448 may, in certain examples, be a mesh or porous sheet that mayallow air to flow through the inner sheet 448. A further example of sucha porous sheet may be a feltmetal sheet that has a cross-linkedstructure. The feltmetal structure may be a matrix of wire and/or mesh,for example a regular or irregular cross-linked structure made of aferromagnetic metal wire, sponge, or other porous media. In certainexamples, the inner sheet 448 may be at least partially constructed froma ferromagnetic metal. In certain such examples where the inner sheet448 is a feltmetal, the matrix of the feltmetal may be at leastpartially ferromagnetic metal.

Certain examples of the skin 400C may not perfectly align the holes orporous portion of the inner sheet 448 with the holes or porous portionof the facesheet 440. Such misalignment may affect the flow of airthrough the facesheet 440 and/or the inner sheet 448 and thus, themisalignment may be used to tune such flow and change the noiseattenuation characteristics of the skin.

In addition to the configurations described, other skin configurationsmay also be used with the inductive coil anti-icing and noise absorptionsystem. For example, an additional insulating layer may be installedbetween the facesheet 440 and the inner sheet 448 of the skin 400C. Theinsulating layer may aid in the retention of heat generated by thefacesheet 440 and/or the inner sheet 448 and may, accordingly, decreasethe number of electromagnetic generation cycles of the inductive coil418. Additionally, the facesheet 440 may not be present in certainexamples. Instead, the supporting structure may include feltmetal mesh,possibly containing ferromagnetic metal, melted into the supportingstructure.

In certain examples that use the skin at multiple locations on theaircraft, the skin may vary in thickness depending on the area ofapplication. In certain such examples, the porous skin may be thethickest near a lip region (i.e., the forward most region) of anaircraft engine nacelle. Certain other such examples may vary thethickness of the skin depending on the noise source of the noise thatneeds to be attenuated. For example, different noise frequencies may beattenuated with different thicknesses.

One, some, or all of the various skin configurations described hereinmay be incorporated into an inductive coil anti-icing and noiseabsorption system. The inductive coil anti-icing and noise absorptionsystem may be mounted on an aircraft and may perform anti-icing andnoise absorption functions concurrently. The functions may be performedat least when the aircraft is operational. FIG. 5 illustrates aflowchart detailing an operation of an inductive coil anti-icing andnoise absorption system in accordance with the disclosure.

In step 500, the aircraft may be operational. The engine of the aircraftmay be operational and air may flow through the components of theaircraft.

In step 502, power may be provided to the inductive coil(s). Power maybe provided to the inductive coil(s) in any manner described herein.When the inductive coil(s) are powered, the inductive coil(s) maygenerate an electromagnetic field or multiple electromagnetic fields instep 504.

The electromagnetic fields generated in step 504 may be captured by askin in step 506. The skin may be electromagnetically excited by theelectromagnetic field. The skin, when electromagnetically excited, maygenerate heat in step 510. In certain examples, at least a portion ofthe skin may be porous.

In step 512, air may flow through the porous portion of the skin. Airmay flow through, for example, a porous facesheet, a septum, an innersheet, or other component of the skin. The airflow through the skin mayattenuate noise in step 514. The noise attenuation steps 512 and 514 mayoccur concurrently with steps 502 to 510.

The inductive coil anti-icing and noise absorption system may beassembled to the aircraft using certain techniques. An example of such atechnique is shown in FIG. 6. FIG. 6 illustrates a flowchart detailingan assembly process of an aircraft component containing an inductivecoil anti-icing and noise absorption system in accordance with thedisclosure.

In step 602, the skin may be manufactured. The skin manufactured may beany version of the skins detailed in FIGS. 4A-C herein. The skin mayinclude a component containing ferromagnetic metal. The component mayincorporate ferromagnetic metal through the base material, through atleast one coating, through deposition, through structurally orcosmetically linking the ferromagnetic material to another material, orthrough any other technique. In certain examples, more than one of thetechniques described may be used to incorporate the ferromagnetic metalinto the component.

In step 604, the skin may be coupled to the aircraft. The skin may, forexample, be installed to an engine (i.e., on the engine nacelle), a wingor other airfoil, or a fuselage of the aircraft.

In step 606, the inductive coil may be installed on the aircraft. Incertain examples, the inductive coil may be positioned within a cavitythat is at least partly defined by the skin installed on the aircraft.At least a part of the inductive coil may be positioned within 1-2inches of at least a part of a skin. While the example described in FIG.6 may perform step 604 before 606, certain other examples may performstep 606 before step 604, or may perform portions of or the entirety ofstep 604 and portions of or the entirety of step 606 concurrently.

In step 608, the inductive coil may be connected to the power source.The power source may additionally be connected to a controller. Thecontroller may have previously been connected to the power source, maybe connected to the power source when the inductive coil is connected tothe power source, or may be connected to the power source after theinductive coil has been connected to the power source. After step 608,certain examples may then perform further assembly steps. For example,where the skin and inductive coil are components of an aircraft engine,the aircraft engine may then be further installed onto a fuselage, wing,or other engine mounting point of the aircraft.

Examples described above illustrate but do not limit the invention. Itshould also be understood that numerous modifications and variations arepossible in accordance with the principles of the present invention.Accordingly, the scope of the invention is defined only by the followingclaims.

What is claimed is:
 1. An apparatus comprising: a portion of a nacellecomprising a skin, wherein: the skin comprises a ferromagnetic porousfacesheet configured to electromagnetically couple with anelectromagnetic field to generate heat, a ferromagnetic porous innersheet disposed apart from and behind the porous facesheet, and anon-ferromagnetic backsheet coupled to the porous facesheet and theporous inner sheet, wherein the porous facesheet is made of a firstsmart susceptor configured to couple with an inductive coil at a firstresonant frequency to be heated to a first temperature, and wherein theporous inner sheet is made of a second smart susceptor configured tocouple with the inductive coil at a second resonant frequency to beheated to a second temperature different from the first temperature; atleast a portion of the skin forms a flow surface of the nacelle; and theskin at least partly defines a cavity.
 2. The apparatus of claim 1,wherein an opening of the porous facesheet is misaligned with an openingof the porous inner sheet.
 3. The apparatus of claim 1, wherein theinner sheet comprises a cross-linked structure.
 4. The apparatus ofclaim 1, wherein the porous facesheet is comprised of or coated with aferromagnetic metal and at least a portion of the skin is located on aleading edge of the nacelle.
 5. The apparatus of claim 1, wherein theskin further comprises a support component between the porous facesheetand the backsheet, and wherein the support component comprises ahoneycomb.
 6. The apparatus of claim 1, wherein the inner sheetcomprises at least one of a plurality of perforations, a mesh, a porousmat, or a regular or irregular cross-linked structure made of aferromagnetic metal wire, sponge, or other porous media.
 7. Theapparatus of claim 1, wherein the porous facesheet is configured toattenuate noise.
 8. The apparatus of claim 1, further comprising theinductive coil, wherein the inductive coil is located at least partlywithin the cavity and configured to electromagnetically couple to theporous facesheet and the porous inner sheet, wherein the porousfacesheet and the porous inner sheet are configured to increase intemperature when electromagnetically coupled to the inductive coil, andwherein the inductive coil is configured to operate at the firstresonant frequency and the second resonant frequency.
 9. The apparatusof claim 8, wherein the inductive coil is a first inductive coil, theskin is a first skin, the ferromagnetic porous facesheet comprises afirst ferromagnetic metal, and further comprising a second skin and asecond inductive coil such that: the second skin at least partly definesthe cavity; the second skin is comprised of the first ferromagneticmetal and/or a second ferromagnetic metal; the first inductive coil isconfigured to be electromagnetically coupled to the first skin; and thesecond inductive coil is configured to be electromagnetically coupled tothe second skin.
 10. The apparatus of claim 9, wherein the second skinis non-porous.
 11. The apparatus of claim 1, wherein the inner sheetcomprises a sound absorber comprising a fiber bulk absorber, a foamlayer, and/or a porous mat.
 12. The apparatus of claim 1, wherein theinner sheet is disposed adjacent to the facesheet.
 13. The apparatus ofclaim 12, wherein the inner sheet is disposed adjacent to the facesheet,wherein the facesheet comprises first openings, wherein the inner sheetcomprises second openings, and wherein the first openings and the secondopenings are misaligned such that at least a portion of the secondopenings is obscured by a portion of the facesheet.
 14. An aircraftcomprising the apparatus of claim 1 and: a fuselage; a wing coupled tothe fuselage; an engine coupled to the wing, the fuselage, or both,wherein at least one of the fuselage, the wing, and/or the engineincludes the apparatus.
 15. A method comprising: receiving a skincomprising at least a ferromagnetic porous facesheet, a ferromagneticporous inner sheet disposed apart from and behind the porous facesheet,and a non-ferromagnetic backsheet, wherein the porous facesheet is madeof a first smart susceptor configured to electromagnetically couple withan electromagnetic field at a first resonant frequency to be heated to afirst temperature, and wherein the porous inner sheet is made of asecond smart susceptor configured to electromagnetically couple with theelectromagnetic field at a second resonant frequency to be heated to asecond temperature; and coupling the skin to an engine to form at leasta portion of an engine nacelle, wherein at least a portion of the skinforms a flow surface of the engine nacelle.
 16. The method of claim 15,further comprising: installing an inductive coil within a cavity of theengine nacelle; electrically connecting the inductive coil to a powersupply; and positioning at least a portion of the skin within 1-2 inchesof at least a portion of the inductive coil.
 17. The method of claim 16,wherein the skin is a first skin, the inductive coil is a firstinductive coil, the ferromagnetic porous facesheet comprises a firstferromagnetic metal, and the method further comprises: coupling a secondskin to the engine, wherein a portion of the second skin is comprised ofthe first ferromagnetic metal and/or a second ferromagnetic metal;installing a second inductive coil within the cavity of the enginenacelle, wherein at least a portion of the second skin is within 1 footof at least a portion of the second inductive coil; and electricallyconnecting the second inductive coil to the power supply or a secondpower supply.
 18. The method of claim 17, wherein the power supply is afirst power supply and the method further comprises connecting thesecond inductive coil to the second power supply.
 19. The method ofclaim 15, wherein the inner sheet is disposed adjacent to the facesheet,wherein the facesheet comprises first openings, wherein the inner sheetcomprises second openings, and wherein the first openings and the secondopenings are misaligned such that at least a portion of the secondopenings is obscured by a portion of the facesheet.
 20. The method ofclaim 15, wherein the inner sheet comprises a sound absorber and isdisposed adjacent to the facesheet, and wherein the sound absorbercomprises a fiber bulk absorber, a foam layer, and/or a porous mat. 21.A method comprising: moving a vehicle with an engine, wherein the engineincludes a nacelle and at least a portion of the nacelle comprises askin comprising a ferromagnetic porous facesheet, a ferromagnetic porousinner sheet disposed apart from and behind the porous facesheet, and anon-ferromagnetic backsheet, wherein the porous facesheet is made of afirst smart susceptor configured to electromagnetically couple with anelectromagnetic field at a first resonant frequency to be heated to afirst temperature, and wherein the porous inner sheet is made of asecond smart susceptor configured to electromagnetically couple with theelectromagnetic field at a second resonant frequency to be heated to asecond temperature; flowing air through the porous facesheet; andattenuating noise by, at least, the flowing of air through the porousfacesheet.
 22. The method of claim 21, wherein an opening of the porousfacesheet is misaligned with an opening of the porous inner sheet, andwherein the method further comprises flowing air through the porousinner sheet.
 23. The method of claim 22, wherein the inner sheet isferromagnetic and the method further comprises: generating theelectromagnetic field with an inductive coil; electromagneticallycoupling, with the electromagnetic field, the inductive coil to theferromagnetic facesheet and/or the inner sheet; and increasing, byelectromagnetically coupling the electromagnetic field to the facesheetand/or the inner sheet, temperatures of the facesheet and/or innersheet.
 24. The method of claim 23, wherein inner sheet comprises across-linked structure.
 25. The method of claim 23, wherein the innersheet separates the skin into a first compartment and a secondcompartment and the method further comprises varying the temperaturebetween the first compartment and the second compartment by heating thefirst smart susceptor to the first temperature and the second smartsusceptor to the second temperature.
 26. The method of claim 21, whereinthe attenuating noise by the flowing of air through the facesheetcomprises attenuating noise generated by the engine.